API 6A Test Flange - Which test connection type to use

[kat6787]

Good morning,

I've got a question related to the test flange requirements in API6A. We have piping segments that will be installed offshore and will have 10K API 6BX flanges on either end. In order to test the segments prior to going offshore we are looking to have test ports tapped but I am a little confused at which test port will be required under API6A.

MAOP of Pipe segments = 9,000psi
Hydrotest Pressure = 11,250psi
Leak Test (after installation) = 9,900psi

Table B.57 and B.58 provide test port information based on working pressure. Is this working pressure of the flange, or should it be based on the highest test pressure?

My personal preference would be to go with the higher rating and use an Autoclave tapped test port, because Autoclave connections do better in high pressure testing. NPT will work, but not as well in my experience. But using Autoclave significantly increase the cost, so the higher ups are looking for a more definitive reason to go with the more expensive option.

Will also throw in that I am a pre-commissioning engineer, not a structural engineer or flange expert. From my side, I can provide any fitting to match the required pressure. I'm just trying to better understand the code requirements as there has been some disagreement between folks in the office about what to use.

Cheers,
Kat

 

[jbeckhou]

kat6787

Table B.57 and B.58 refer back to figure 19, which is a 9/16" AEHP port (30k rated port). You can use, 9/16" AEHP or 1/2" NPT (10k max WP, 15k max TP)for you flange. I would recommend using 9/16" port rather then NPT if you plan on using the flanges more then once. Question, why is your Test pressure only 2250 (1.25 x WP) psi higher than WP? Are the piping segments rated and built to API-6A?

Petrotrim Services, LLC

http://www.petrotrim.com

 

[kat6787]

Thanks for your response. I must have missed where they discuss the 15k max TP. I'll have to go back and look at Figure 19 again. We finally got a decision to go with the 9/16" connection.

The test pressure for this test is based on 30 CFR 250 requirements as the piping will be outboard of the shutdown valve. The individual piping segments are tested to higher as part of the manufacturing process (although I would have to get with the project engineer to know exactly what pressure), but for BSEE requirements, 1.25 x WP is all that is required.

 

[jbeckhou]

Note: 15k TP was only for the 1/2" NPT.

Petrotrim Services, LLC

http://www.petrotrim.com

 

[ricklts]

kat6787,

I agree completely with jbeckhou. Besides, if you ever need to use the same flange to test a true API 6BX10K connection, the hydro pressure will be 15K, too close for comfort with 1/2"NPT.

Rick